The Pure Data (short Pd) project on SourceForge unifies the extensions (or externals) written for the Pure Data Graphical Computer Music System written by Miller Puckette with contributions from many others.

Source Navigator NG is a source code analysis tool.
With it, you can edit your source code, display relationships between classes and functions and members, and display call trees.
You can navigate your source code and easily get to declarations or implementations of functions, variables and macros (commonly called "symbols") which helps you discovering and mapping unknown source code for enhancement or maintenance tasks.

GraphicsMagick provides a set of commandline tools and programming APIs for manipulating, editing, and converting raster and vector images. It is derived from ImageMagick, with the objective of providing better stability and performance than ImageMagick.

Tux Racer is a simple OpenGL-based racing game featuring Tux, the Linux Penguin. The object of the game is to slide down a snow- and ice-covered mountain as quickly as possible, avoiding the trees and rocks that will slow you down.

ASCEND is a modelling environment and solver for large or small systems of non-linear equations, for use in engineering, thermodynamics, chemistry, physics, mathematics and biology. Solvers for both steady and dynamic (NLA & DAE) problems, are provid

ChessDB is a free open-source chess database for Windows, Linux, Mac OSX and most UNIX and UNIX-like operating systems. ChessDB is based on code from Scid http://scid.sourceforge.net/ - a project for which there have been no updates for several years. In

Repeater controller and EchoLink software for Linux including a GUI, Qtel - the Qt EchoLink client.
The SvxLink project has now moved to GitHub. The new home page for the project is http://svxlink.org/ .

OTcl, short for MIT Object Tcl, is an extension to Tcl/Tk for object-oriented programming. TclCL (Tcl with classes) is a Tcl/C++ interface used by Mash, vic, vat, rtp_play, ns, and nam. It provides a layer of C++ glue over OTcl.

TkDND is an extension that adds native drag & drop capabilities to the Tk toolkit. It can be used with any Tk version equal or greater to 8.3.3 and currently only the UNIX (X-Windows), Microsoft Windows (XP, Vista, 7) and OS X (Leopard) operating systems.
Please note that sources have been moved to: https://code.google.com/p/tkdnd/

LinuxCNC performs real-time control of equipment such as machine tools, robots, and coordinate measuring machines. It runs in realtime under Linux with the RTlinux or RTAI patch. It provides a software PLC, and uses the HAL for flexibility.

A modular framework for implementing a CISCO-like CLI on a *NIX system. Arbitary command menus and actions can be defined using XML files. This software handles the user interaction, and forks the appropriate system commands to perform any actions.

EMU is a collection of software tools for the creation, manipulation and analysis of speech databases. At the core of EMU is a database search engine which allows queries based on the sequential and hierarchical structure of the annotations.